Steel truss



July 21, 1.925.

' H. R. BRADLEY STEEL TRUS S Filed Jan. 14, 1922 ATTORNEY.

Patented July 21, 1925.

UNITED STATES HALBERT R. BRADLEY, OF CHICAGO, ILLINOIS.

STEEL 5331158.

Application filed January 14, 1922. Serial No. 529,121.

To all whom it may concern.

Be it known that I, I-IALBERT R. BRADLEY, a citizen of the UnitedStates, and resident of Chicago, in the county of Cook and State ofIllinois, have invented certain new and useful Improvements in SteelTrusses, of which the following is a specification.

This invention relates to steel trusses and relates particularly tosteel trusses fabricated from commercially available steel sections,especially designed and adapted for supporting the roofs of relativelywide buildings-as the roofs of garages -in which an unobstructed floorspace is desired.

At the present time, trusses for the'purpose specified are generallymade of wood and are relatively cheap, and in order that steel trussesmay compete commercially with such wood trusses, it is necessary thatthey shall be sodesigned that the weight of the metal contained thereinand the cost of fabrication shall be reduced to a minimum, while, at thesame time, providing requisite strength in the structure.

Also, buildings such as those in which my improved truss will be usedmost extensively, are lighted principally by means of skylights, and inorder that the roof trusses shall. obstruct the passage of light aslittle as possible, it is desirable that the trusses shall consist ofrelatively few parts and that they shall be as small as possible,consistent with requisite strength.

Stated broadly, therefore, the objectof my invention is to provide asteel truss for the purposes specified, which can be manufactured atsuch small cost that it can compete comn'iercially with the woodentrusses now generally used.

To effect theobjects of the invention, my improved truss comprises abowed top chord, a bottom chord comprising end sections which areupwardly and inwardly inclined relative to a right line connecting theends of the trusshereinafter, for purposes of convenient reference,designated as the base lineand an intermediate section which eX- tendsparallel with said base line, and web members comprising twoinclinedmembers at each end of the truss which connect the inner ends of theinclined bottom chord sections with the top chord, the points ofconnection of said inclined web members to said top chord being definedby the inter section therewith of the extreme four of at least sixlineshereinafter designated ordinatesprojected upwardly from points inthe base line of the truss which divide it into parts of equal lengthand the inner ends of the inclined bottom chord sections terminatmgsubstantially at the third ordinates from the outer ends of saidinclined bottom chord sections, respectively, said web members alsocomprising upright members which connect the top and bottom chords, twoof which are substantially coincident with the third ordinates from theends of the truss, and diagonal bracing members which connect the upperand lower ends, respectively, of adjacent upright web members.

My improved truss also comprises the various other features and detailsof con struction hereinafter described and claimed.

In the accompanying drawing,

The figure is a side view of a truss embodying my invention andimprovements.

Describing my improved truss with particular reference to the drawing, Adesignates the truss, as a whole, said truss co1nprising a bowed topchord 1, a bottom chord comprising end sections 2, 2, which are inwardly and upwardly inclined to the base line of the truss, indicated bythe dotted line 3, and an intermediate section 22 which extends parallelwith said base line.

The inclination of the bottom chord sections 2, 2 to the base line ofthetruss is approximately eight (8) degrees and is constant for all trussesembodying my inven tion and improvements regardless of their length.

In the preferable embodiment of my invention the curvature of the topchord 1 is ascertained and determined in the following manner: From atleast six points in the base line 3 which divide it into parts of equallength, lines l, 4, 4 4?, 4L, 4 and 4. are projected backwardly, saidlines, for purposes of convenient reference being hereinafter designatedordinates.

Reckoning from the base line, the height of the truss at the ordinates4:, 4 is approximately twelve (12%) per cent of the length of the truss;at the ordinates 4, 4 approximately seventeen (17%) per cent of thelength of the truss; and at the ordinates 4 4 approximately eighteen(18%) per cent of the length of the truss, These points define points inthe top chord and the curvature of said top chord may be determined withsufiicient accuracy for usual purposes, by arcs ot c1rcles which passthrough the ends of the truss end the location points in the ordinates4t, 4t and 4 l, adjacent to opposite ends of the truss, and the arc of acircle which passes through the location points in the ordinates 4L and4 and which merges into the arcs which define the curvatures of the endsections of the truss lhe inner ends of the inclined bottom chordsections terminate substantially at the third ordinates from the outerends of said inclined sections, respectively.

My improved truss also comprises web members 5, 5, 5. and 5 whichconnect the inner ends 01 the inclined bottom chord sections 2, 2, withthe top chord at the points. therein defined by the intersectionstherewith of the ordinates 4:, 41 and P, a, respectively. Said webmembers also comprise upright members 5 and 5 which connect the innerends of the bottom chord sections with the top chords and which aresubstantially coincident with the ordinates 4 and 4- respectively.

The web members also comprise diagonal bracing members 5 and 5 vhichconnect the top and bottom chords at the upper and lower ends,respectively, of the upright web members 5*, 5 As shown, saie diagonals5, 5 are rigidly connecting where they cross each other and areconnected with the middle of the top chord of an upright member 5Excepting for variations in dimensions, the end sections of the trussshown in the drawing and which may be designated, respectively, A A andwhich are formed by the ends of the top chord, the inclined end sectionsof the bottom chord, and the web members 5 to- 5", are, respectively,substantially duplicates in all trusses embodying my invention andimprovements, but the bracing between the upright members 5 and may bevariously modified within the scope of my invention.

I claim 1. In a steel truss, the combination of a bowed top chord, abottom chord comprisin end sections which are inwardly and upwardlyinclined to the base line of the truss, and an intermediate sectionwhich extends parallel with said base line, and web men bers comprisingtwo inclined members at each end of the truss which connect the innerends of the inclined bottom chord sec tions with the top chord, theinner ends of the inclined bottom chord sections terminatingsubstantially at the third ordinates from the outer enos of saidsections, respectively, of at least six ordinates projected upwards frompoints in the base line of the truss which divide it into parts of equallength, and the web members also comprising upright members whichconnect the top and bottom chord, two or" which are substantiallycoincident with the third ordinates from the ends of the truss, anddiagonal bracing members which connect the top and bottom chords at theupper and lower ends, respectively, of adjacent upright members.

2. A steel truss as specified in claim 1, in which an upright web memberor members connect the diagonal web members at their intersections, withthe top chord.

In testimony that I claim the foregoing as my invention, I affix mysignature this 11th day of January, 1922.

HALBERT R. BRADLEY.

